Dal Karlton was chief of the Space Security Service (S.S.S.) on Earth in 4000. He assisted Mavic Chen, the Guardian of the Solar System, and was Chen's co-conspirator in the secret alliance with the Daleks.
Loyal to Mavic Chen for as long as it suited his ambitions, Karlton was unaware of both Marc Cory's and Bret Vyon's missions to Kembel, and sent Sara Kingdom, his most ruthless and trusted agent, to stop the truth emerging. He hinted that when the opportunity emerged he would betray Chen and try to replace him. (TV: The Daleks' Master Plan)
After the Daleks had failed, Karlton was confused. The Earth had not been invaded by the Daleks, nor did Chen report back. He was discovered thanks to Marc Cory's recording telling Earth all about Karlton and Chen's plan to conquer the universe by helping the Daleks. He was arrested by Senator Diksen and put on trial for high treason. (PROSE: The Mutation of Time)